School Energy of Research something Institute OTHER Catalytic gasification of biomass for hydrogen production with in-situ CO 2 absorption using novel bi-functional CaO catalyst Mohamad Anas Nahil, Chunfei Wu and Paul Williams
Background Experimental set up Results and discussion Conclusions
Hydrogen is an important future fuel and energy carrier and is predicted to play an important role in future energy systems. Production of hydrogen from renewable resources, such as biomass, would provide a sustainable route for hydrogen production using a source which is carbon neutral. Catalytic gasification of biomass, in the presence of a calcium oxide (CaO) sorbent for CO 2 capture, is an innovative pathway to improve H 2 yield compared to conventional gasification.
Aims of work Preparation of novel bi-functional catalyst by incorporating a CO 2 sorbent (CaO) into a Ni-based catalyst (Ni-Mg-Al). Investigation the efficiency of this catalyst in terms of: - The stability of CaO in relation to CO 2 adsorption. - Hydrogen production from the pyrolysis-gasification of biomass using a two-stage fixed-bed reaction system.
C n H m O z + (n - z) H 2 O nco + (n-z + m/2) H 2 CO + H 2 O CO 2 + H 2 CaO + CO 2 CaCO 3
Experimental procedure Wood biomass. Ni-Mg-Al catalyst 1 : 1 : 1 molar ratio. CaO by adding 0.5, 1, 2 and 3g of CaO Reaction temperatures, 600 o C top and 800 o C bottom. Steam injection rates 4.74 g/h 1g catalyst and 2g sample
Mass(mg) Mass(mg) Mass(mg) Energy Research Institute Results and Discussion TGA curves recorded during the carbonation/calcination reaction cycles of different CO 2 sorbents 13 CaO 11.2 2CaO 12 11.0 11 40 % 10.8 10 9 10.6 8 0 100 200 300 400 500 600 Time (min) 11.0 10.4 0 100 200 300 400 500 600 3CaO Time (min) 10.5 10.0 9.5 0 100 200 300 400 500 600 Time (min)
SEM results of the fresh and tested (after multiple carbonation/ calcination cycles with TGA) CO 2 capture sorbents To summarize: The incorporation of CaO into Ni-Mg-Al catalyst will improve the stability of the catalyst/sorbent for CO 2 capture compared to pure CaO sorbent.
Product yields and the gas composition from the pyrolysis-gasification of wood biomass. Catalyst Blank Ni-Mg-Al 0.5CaO 1CaO 2CaO 3CaO CaO content * - 0 11.1 20 33.3 42.9 Conversion ** 66.5 66.0 65.5 64.0 64.5 64.0 Gas yield 40.7 64.2 54.5 60.9 56.4 54.3 Hydrogen 3.6 20.4 15.3 20.2 14.4 13.7 (mmol g -1 biomass) H 2 /CO 0.037 0.128 0.137 0.138 0.149 0.160 (g g -1 ) Hydrogen selectivity (%) 23.4 63.2 59.6 63.7 60.9 59.1 Gas concentrations (vol.%) CO 38.3 29.8 25.8 28.1 22.9 20.9 H 2 19.9 52.9 49.0 53.9 47.4 46.4 CO 2 14.7 16.0 17.6 15.2 22.0 21.4 CH 4 21.4 1.2 5.9 2.1 6.0 8.9 C 2 -C 4 5.7 0.1 1.8 0.7 1.7 2.5 * CaO content was calculated as weight of CaO divided by the weight of CaO catalyst ** Conversion is calculated as (100 wt.% - residue wt.%)
The effect of catalyst addition Catalyst Blank Ni-Mg-Al 0.5CaO 1CaO 2CaO 3CaO CaO content * - 0 11.1 20 33.3 42.9 Conversion ** 66.5 66.0 65.5 64.0 64.5 64.0 Gas yield 40.7 64.2 54.5 60.9 56.4 54.3 Hydrogen 3.6 20.4 15.3 20.2 14.4 13.7 (mmol g -1 biomass) H 2 /CO 0.037 0.128 0.137 0.138 0.149 0.160 (g g -1 ) Hydrogen selectivity (%) 23.4 63.2 59.6 63.7 60.9 59.1 Gas concentrations (vol.%) CO 38.3 29.8 25.8 28.1 22.9 20.9 H 2 19.9 52.9 49.0 53.9 47.4 46.4 CO 2 14.7 16.0 17.6 15.2 22.0 21.4 CH 4 21.4 1.2 5.9 2.1 6.0 8.9 C 2 -C 4 5.7 0.1 1.8 0.7 1.7 2.5 * CaO content was calculated as weight of CaO divided by the weight of CaO catalyst ** Conversion is calculated as (100 wt.% - residue wt.%)
Catalyst Blank Ni-Mg-Al 0.5CaO 1CaO 2CaO 3CaO CaO content * - 0 11.1 20 33.3 42.9 Ni content (mol%) EDX 14.0 11.7 9.8 6.2 3.4 Conversion ** 66.5 66.0 65.5 64.0 64.5 64.0 Gas yield 40.7 64.2 54.5 60.9 56.4 54.3 Hydrogen 3.6 20.4 15.3 20.2 14.4 13.7 (mmol g -1 biomass) H 2 /CO 0.037 0.128 0.137 0.138 0.149 0.160 (g g -1 ) Hydrogen selectivity (%) 23.4 63.2 59.6 63.7 60.9 59.1 Gas concentrations (vol.%) CO 38.3 29.8 25.8 28.1 22.9 20.9 H 2 19.9 52.9 49.0 53.9 47.4 46.4 CO 2 14.7 16.0 17.6 15.2 22.0 21.4 CH 4 21.4 1.2 5.9 2.1 6.0 8.9 C 2 -C 4 5.7 0.1 1.8 0.7 1.7 2.5 * CaO content was calculated as weight of CaO divided by the weight of CaO catalyst ** Conversion is calculated as (100 wt.% - residue wt.%)
The effect of CaO addition Catalyst Blank Ni-Mg-Al 0.5CaO 1CaO 2CaO 3CaO CaO content * - 0 11.1 20 33.3 42.9 Conversion ** 66.5 66.0 65.5 64.0 64.5 64.0 Gas yield 40.7 64.2 54.5 60.9 56.4 54.3 Hydrogen 3.6 20.4 15.3 20.2 14.4 13.7 (mmol g -1 biomass) H 2 /CO 0.037 0.128 0.137 0.138 0.149 0.160 (g g -1 ) Hydrogen selectivity (%) 23.4 63.2 59.6 63.7 60.9 59.1 CO + H 2 O CO 2 + H 2 Gas concentrations (vol.%) CO 38.3 29.8 25.8 28.1 22.9 20.9 H 2 19.9 52.9 49.0 53.9 47.4 46.4 CO 2 14.7 16.0 17.6 15.2 22.0 21.4 CH 4 21.4 1.2 5.9 2.1 6.0 8.9 C 2 -C 4 5.7 0.1 1.8 0.7 1.7 2.5 * CaO content was calculated as weight of CaO divided by the weight of CaO catalyst ** Conversion is calculated as (100 wt.% - residue wt.%)
The effect of CaO with similar Ni content Catalyst Blank Ni-Mg-Al 0.5CaO 1Quartz 1CaO 2CaO 3CaO CaO content * - 0 11.1-20 33.3 42.9 Conversion ** 66.5 66.0 65.5 65.5 64.0 64.5 64.0 Gas yield 40.7 64.2 54.5 51.9 60.9 56.4 54.3 Hydrogen 3.6 20.4 15.3 14.9 20.2 14.4 13.7 (mmol g -1 biomass) H 2 /CO 0.037 0.128 0.137 0.099 0.138 0.149 0.160 (g g -1 ) Hydrogen selectivity (%) 23.4 63.2 59.6 55.8 63.7 60.9 59.1 Gas concentrations (vol.%) CO 38.3 29.8 25.8 35.3 28.1 22.9 20.9 H 2 19.9 52.9 49.0 48.6 53.9 47.4 46.4 CO 2 14.7 16.0 17.6 12.6 15.2 22.0 21.4 CH 4 21.4 1.2 5.9 2.8 2.1 6.0 8.9 C 2 -C 4 5.7 0.1 1.8 0.7 0.7 1.7 2.5 * CaO content was calculated as weight of CaO divided by the weight of CaO catalyst ** Conversion is calculated as (100 wt.% - residue wt.%)
To summarize: Biomass Catalytic steam reforming of hydrocarbons reaction Water gas shift reaction * Without CaO With CaO
Temperature Programmed Oxidation (a) and TGA-CO 2 absorbance peak (b) results of the reacted Ni-Mg-Al catalyst with different contents of CaO CaCO 3 CaO + CO 2
Conclusions Carbonation/calcination results using TGA analysis in the presence of a N 2 or CO 2 atmosphere showed that the stability of CO 2 adsorption using CaO was enhanced when CaO was incorporated into the Ni-Mg- Al catalyst. The increase of CaO content in the Ni Mg Al catalyst system was found to increase the H 2 /CO ratio during biomass gasification. Hydrogen production was suggested to be controlled by two main routes: (1) hydrocarbon conversion and (2) water gas shift reaction enhanced by CO 2 adsorption. Reacted catalysts characterized by TPO-FTIR results showed that carbon deposition was significantly reduced when CaO was added to the Ni Mg Al catalyst. In addition, carbon deposition was also found to be reduced with an increased CaO content in the catalyst system.
Thank you for your attention! Mohamad Nahil m.a.nahil@leeds.ac.uk